answers to usual issues in getting started with consuming linked data

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

GettingStarted

Issues people have when they want to start

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

Getting Started

Finding URIs

Finding Additional Data

Finding SPARQL Endpoints

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

Finding URIs

● Problem: What URIs exist that identify the thing I'm interested in?

● Two options:● Data source specific solutions● Search engines for the Web of Linked Data

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

Finding URIs

● Some Linked Data sources provide a keyword-based search for things in their dataset(s)● RKB Explorer http://www.rkbexplorer.com/● DBpedia http://lookup.dbpedia.org/

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

Finding URIs

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

Finding URIs

● What if there is no search possibility?● You may try a SPARQL query:

SELECT DISTINCT ?s WHERE { ?s rdfs:label ?label . FILTER regex( str(?label), "Berlin", "i" ) .}

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

Finding URIs

● Search engines for the Web of Linked Data provide keyword-based search for things in different datasets● Falcons http://iws.seu.edu.cn/services/falcons/● Sindice http://sindice.com● SWSE http://www.swse.org● Watson http://watson.kmi.open.ac.uk

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

Finding URIs

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

Finding URIs

● There are also APIs● Falcons

http://iws.seu.edu.cn/services/falcons/api/index.jsp● Sindice

http://sindice.com/developers/api● Watson

http://watson.kmi.open.ac.uk/REST_API.html

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:foaf="http://xmlns.com/foaf/0.1/" xmlns:dc="http://purl.org/dc/elements/1.1/"> <foaf:Document rdf:about="http://iws.seu.edu.cn/services/falcons/api/objectsearch.jsp?query=Berlin"> <dc:description>Provides at most 10 objects hit by the query Berlin.</dc:description> <dc:title>Objects hit by the query Berlin</dc:title> <dc:creator>Falcons API</dc:creator> </foaf:Document> <rdf:Seq> <rdf:li rdf:resource="http://dbpedia.org/resource/Berlin"/> <rdf:li rdf:resource="http://dbpedia.org/resource/Category:Berlin"/> <rdf:li rdf:resource="http://dbpedia.org/resource/Category:People_from_Berlin"/> <rdf:li rdf:resource="http://www.deadjournal.com/interests.bml?int=berlin"/> <rdf:li rdf:resource="http://dbtune.org/jamendo/tag/berlin"/> <rdf:li rdf:resource="http://www4.wiwiss.fu-berlin.de/bookmashup/subject/Berlin"/> <rdf:li rdf:resource="http://www.liveinternet.ru/journal_interest.php?interestid=51320"/> <rdf:li rdf:resource="http://wiki.sembase.at/index.php/_Berlin"/> <rdf:li rdf:resource="http://dbpedia.org/resource/Category:Berlin_U-Bahn_stations"/> <rdf:li rdf:resource="http://dbpedia.org/resource/Category:Berlin_culture"/> </rdf:Seq></rdf:RDF>

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

Getting Started

Finding URIs

Finding Additional Data

Finding SPARQL Endpoints

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

Finding Additional Data

● Problem: Given a URI, where do I find more data as what is available by looking it up?

● Three options:● Follow links (e.g. rdfs:seeAlso, owl:sameAs)● Use a co-reference service● Use a search engine for the Web of Linked Data

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

Finding Additional Data

● Co-reference services find different URIs that refer to the same thing● sameAs http://sameas.org

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

Finding Additional Data

● There is also an API

● Specify the preferred format in the URI

● Use content negotiation

http://sameas.org/rdf?uri=http://dbpedia.org/resource/Berlin

http://sameas.org/n3?uri=http://dbpedia.org/resource/Berlin

http://sameas.org/json?uri=http://dbpedia.org/resource/Berlin

GET /?uri=http://dbpedia.org/... HTTP/1.1Host: sameas.orgAccept: application/rdf+xml

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

Finding Additional Data

● Search engines for the Web of Linked Data provide URI-based search for data from different sources● Sindice http://sindice.com

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

Getting Started

Finding URIs

Finding Additional Data

Finding SPARQL Endpoints

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

Finding SPARQL Endpoints

● Look at: http://esw.w3.org/topic/SparqlEndpoints

● SPARQL 1.1 Service Description● Vocabulary of Interlinked Datasets (voiD)